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Abstract

In this communication, we show how a short-pitch diffractive structure can be used as a low-cost high sensitivity device for refractive index measurements with sensitivity of 10−2. The device consists of a photo-resist diffraction grating put in optical contact with a hollow prism used as a container for a test material. Its main advantage is the possibility to monitor the composition of solids, fluids and gases in real time. Knowledge of optical parameters of a system with high accuracy can be vital when working in the biological/medical field.

Figures (4)

Sketch of the device. A hollow prism contains tiny volumes of test materials and a diffraction grating is put in optical contact with one of its surfaces. Light is normally incident on the external surface of the prism and propagates without refraction throughout materials. The angle of incidence on the grating surface (α) and that of diffraction (β) are related to the refractive index nmat of the test material.